Fireproofing of wood



starts PATENT @FMBE.

HOWARD r. wnrss, or MADISON, WISCONSIN, ASSIGNOR TO 0. r. BURGESSLABORA- romnsor MADISON, WISCONSIN, A conroanrron OF WISCONSIN.

rianrnoormo or woon.

No Drawing.

- To all whom it may concern:

4 results, so that their effectiveness gradually Be it known that I,HOWARD F. WEIss, a citizen of the United States, residing at Madison, inthe county of Dane, State of Wisconsin, have invented certain new anduseful Improvements in Fireproofing of WVood; and I do hereby declarethe following to be a full, clear, and exact description of theinvention, such as will enable others skilled in the art to which itappertains to make and use the same.

In the fire-proofing of wood, to which the present invention relates, ithas heretofore been customary to treat the wood, especially when in theform of shingles, in one or the other of two ways, viz: either bydipping'the wood into, or painting it with, a liquid fire-proofingcomposition, or by injecting a, Water soluble fire-resisting chemical'ofsome character into the wood. Both of these treatments, however, aresuperficial only, and produce merely temporary becomes impaired, andthey must, in consequence, be repeated from time to time. Thus, in thefirst instance, the paint wears off and furthermore, if the paintedsurface is once punctured by the fire, the wood on the inside is fullycombustible. lln the second instance, the chemicals usually employed,such as ammonium phosphatefammonium sulfate, etc., are soluble in water,and it becomes necessary, therefore to coat the surface of the wood witha substance which will prevent them from washing out.

- Here again, the treatment is temporary only, as the outside protectivecoating wears off in time and, unless renewed, leaves the solublechemicals free to be washed out.

. It has been proposed to Overcome the defects of the aforesaid methodsby injecting into the wood two water soluble chemicals, for example zincchlorid and b'orax, which are capable of combining and forming a' salt(zinc borate) which is insoluble in water. The two chemicals are appliedsepa-.

rately, however, and the wood is dried af ter each impregnation, so thatWhile the 9.0-

' tual results obtained by or from this method have proven satisfactory,the method itself is tedious and'extremely costly.

ltis the object of the present invention to provide a method offireproofing WO0Cl,,

primarily in shingle form, which, while possessing all of the advantagesof the two-v Specification of Letters Patent.

Patented July is, man.

Application filed August 17, 1918. SerialNo. 250,328.

initially and under ordinary conditions soluble in water, but which,-after it has been forced into the wood, will change over into an1nsoluble"chemical upon drying.

Barium sulfid, either crude or refined, has

proven eminently satisfactory for this purpose; and in carrying theinvention into practice, a solution of that chemical is forced underpressure into the wood in much the same manner that wood is cre osoted,after which the wood is removed from \the cylinder impregnated with thebarium sulfid solution and allowed to dry in the air, the bariumcombining with carbon dioxid in the atmosphere and changing intoinsoluble barium carbonate, while the sulfur combines with hydrogen toformhydrogen sulfid and eventually passes 'off in the atmosphere. Inthis way, the Wood is ultimately filled with an insoluble chemical,barium carbonate, which renders it permanently fire-resistant to a highdegree and practically non-combustible. Western red cedar shinglestreated according to this method have been subjected to the flame of aBunsen burner for five minutes at" a temperature of 1600 F, no ignitionwhatever taking place, but the shingles merely becoming converted intocharcoal; whereas untreated shingles and the so-called asphalt shinglescovered with crushed stone or slate, burned violently under the sameconditions, and were completely destroyed.

The change of the barium into barium carbonate can be greatly hastenedand facilitated by drying'the wood in an atmosphere containing morecarbon dioxid. This step may be effectively carried out by running theimpregnated Wood into-a kiln, and passing carbon dioxid gas thereintowith the ordinary air, considerable quantities of the gas being readilyobtainable from flue gases. Experiments have shown that while will goover to the insoluble carbonate when the wood is exposed to the air,nevertheless, larger amounts and better results are secured if thedrying is done in an atmosphere containing more carbon dioxid than ispresent ordinarily in the atmosphere.

I claim as my invention:

1. A one-solution method of fireproofing Wood, which comprisesimpregnating the wood with an aqueous solution of a soluble bariumsulfid, and. then converting said sol- Y uble barium compound intoinsoluble bariuni carbonate by treatment with gaseous carbon dioxid,whereby the sulfur of the said barium sulfid is expelled as hydrogensulfid and the said insoluble barium carbonate is-forme d within thebody of the wood extending inwardly from the periphery of the same.

2. The method of fireproofing wood, which comprises impregnating thewood With an aqueous solution of ,a soluble alkaline earth compound, andthen, while 'which comprises impregnating the wood with an aqueoussolution of a soluble alkaline earth sulfid, and then, while drying thewood, converting said soluble compound into an. insoluble alkaline earthcarbonate by treatment with gaseous carbon dioxid.

4. The method of fireproofing wood, which comprises impregnating theWood with an aqueous solution of a soluble barium sulfid, and then,While drying the Wood, converting said soluble compound into insolublebarium carbonate by treatment with gaseous carbon dioxid.

In testimony whereof I aflix my si nature.

' HOWARD F. ISS.

